The present invention relates to toner cartridges and more particularly to a toner cartridge specially adapted to minimize or prevent toner leakage during use and to permit "white glove" installation and removal of the toner cartridge onto and from a toner hopper.
In conventional copying, a transfer plate comprising a layer of photosensitive insulating material affixed to a conductive backing is used to support electrostatic latent images. In the copying process, the photosensitive surface is electrostatically charged and the charged surface is then exposed to a light pattern of the image being reproduced to thereby discharge the surface in the areas where light strikes the surface. The non-discharged areas of the surface thus form an electrostatic charge pattern (an electrostatic latent image) corresponding to the original pattern. The latent image is then developed by contacting it with a finely divided electrostatically attractable powder referred to as toner. The electrostatic charge holds the toner on the image areas. Where the charge is greater, a greater amount of toner is deposited. With this system, the toner image produced corresponds to the light image of the copy being reproduced. Usually, the developed image is then transferred to a suitable transfer member (e.g., paper) and the image is affixed thereto to form a permanent record of the original document.
Since a quantity of the toner is consumed with each copy, new toner must be added periodically to replenish toner spent in making copies. Toner for this purpose is typically carried in a toner cartridge that can be installed into the copier apparatus. The toner cartridge can be installed onto a toner hopper (i.e., the interface of a toner sump or toner bin which forms a reservoir adapted to accept and hold the toner). When copies are made, a developer roll transports tribo-electrically charged toner from the toner bin to the transfer plate.
Molding processes used in the past created toner cartridges having uneven wall thicknesses. This was especially true at the flange portion of the toner cartridge, i.e., the surface area of the toner cartridge contacting the toner hopper of a copier. Since the surface of the flanges of the toner cartridge were uneven, gaps would exist between the flange surface and the mating surface of the toner hopper. As a result, toner would spill or leak into the immediate area. The inherent vibrations existing in copier machine operation magnified this problem. Moreover, such gaps permit foreign materials to enter the toner hopper area and contaminate the held toner.
In addition to overcoming the problem of leakage, facility maintenance and replacement is a constant concern of copier manufactures. In addition, copier firms as well as firms providing routine copier maintenance and servicing must be accomplished to satisfy customers by providing quick service at low cost with acceptable results. In the past, the seal of the toner cartridge was removed immediately prior to inserting the toner cartridge on to the toner hopper creating the possibility of spilling toner. Such spills are obviously unacceptable in most facilities where copiers are used.